Wax emulsions



Patented 1.1, 29, 1947 factory soap with oleic acid.

WAX EMULSIONS James Otis Handy, .Orlando, Fla., assignor to Duzsel Corporation, Dover, Del., 'a corporation of Delaware No Drawing. Application August 22, 1945, Serial No. 812,140

This invention relates to improved compositions for protectively coating fresh fruit, vegetables and the like to prevent the formation of mold, enhance lustre, and retard drying and shrinking of fruits or vegetables.

More particularly the invention relates to an improved emulsion of candelilla wax which is inexpensive to produce, easy to apply to the fruit and which will adhere firmly, enhance the appearance of the fruit and protect it against drying and decay.

11 Claims. (Cl. 99188) My invention relates more specifically to a novel protective composition of the candeiilla wax base for producing a dense, smooth, thin, and lustrous coating which is entirely free from the undesirable stickiness normally inherent in candelilla wax and its compositions.

The invention relates further to a process of preparaing an emulsion which may be stored and shipped in concentrated form, is stable under changing weather and temperature conditions and which will produce uniform and satisfactory results.

I have found that this stickiness of candelilla wax may be removed by proper combination with other components without impairing the adhesive and cohesive qualities of the wax film or its lustre.

In carrying out my invention I emulsify candelilla wax by means of soap, preferably of oleate character. A certain amount of paramn may be added to the wax and will emulsify likewise to extremely fine particle size producing an emulsion which, unlike the usual parafiin coatings of milky appearance, is crystal clear.

I have found a, very satisfactory soap may be produced from oleic acid, commercially available as Red Oil. I prefer brands of low stearic acid content which produce emulsions of particular stability uninfiuenced by considerable temperature changes. Sodium hydroxide, commercially known as caustic soda, produces a very satisowever, soaps of potassium or organic bases such as the ethanolamines may also be used, the main requirement beingthat the soap is neutral. In proportionins the fatty acids and the caustic soda, it should be observed that complete neutralization of the free fatty acids is obtained, and just enough caustic soda. is present to saponify the glycerides naturally present to some extent in all red oils. I

2 have found that absence of free alkali is essential for the stability of the emulsion.

In the preparation of the soap I prefer commercial caustic soda in an aqueous solution of about 4 normal" or- 4N" concentration. This concentration is obtained by dissolving 16 grams of the caustic soda in cc. of water, then testing and diluting until it matches standard 4N hydrochloric acid.

Candelilia wax may be of single refined quality,

also called "crude" or prime" but I prefer the "double refined grade.-

Parafiin of good commercial grades may be used, refined parailin of a melting point of between and Fahrenheit being preferred.

The stickiness normally inherent in candelilla wax and its composition is neutralized by an addition of shellac in solution. Purified shellac free from arsenic and rosin should be used, the bleached grade being preferred.

I prefer to dissolve the shellac in an aqueous solution of ammonia. The strength of the ammonia solution should be exactly determined and the amount used should always slightly exceed the acidity of the shellac.

I have found the stability of the coating emulsion and its wetting qualities are largely and critically dependent on the soap content in relation to the concentration of the emulsion. Best results are obtained with a soap content of between 2.5% and 4.5% in an emulsion containing a total .or 15% solids. For emulsions of greater or lesser concentration, the soap content should be proportionately greater or less; A soap content of about 3% leads to a product of particularly low surface tension insuring good and even wetting of the fruit. If the soap content is decreased or increased beyond the critical limits, the results are inferior and the emulsions are less stable.

A representative formula for my improved emulsion is as follows: I

- I Percent Candelilla wax 7.67 Paraffin 1. 54 Oleic acid (98% to99%) 2. 5'7 Sodium hydroxide (98% to99%) 0.35 Shellac 3. 00 Ammonia water (26 Baum) 0.54 Water -s4. 33

The emulsion is preferably produced in two stages A" and B as follows:

One hundred gallons-or 834 pounds of emulsion A may be produced as follows:

Weighed quantities of candelilla wax, parafiin and red oil are heated in a suitable container to a temperature between 200 and 210 Fahrenheit and well mixed. The mixed and heated batch is run into a steam or water jacketed mixing tank provided with intermesh'ing paddles for mixing and stirring of the contents. The speed of the mixing paddles is preferably adjustable within considerable limits and controllable so that the rate of stirring of the contents may be changed at will during the process.

Into the mixed hot batch of wax and fatty acid in the mixer the necessary amount of 4N sodium hydroxide solution is run while the contents are stirred at a relatively rapid rate. After addition of the sodium hydroxide solution, which may be of room temperature, the stirring is continued for about ten minutes while the temperature of the batch is maintained at about 200 Fahrenheit. The sodium hydroxide causes saponiflcation of the fats and fatty acids, the soaps producing an emulsion of the water-in-oil type.

Water of about 210 Fahrenheit is then slowly added to the water-in-oil emulsion while constantly stirring, resulting in thickening of the contents to a mobile paste or Jelly. During the I in-oil emulsion to thin and to change gradually to an oil-in-water emulsion. The finished 100 gallons of emulsion "A is then drained of! into steel drums which are atonce closed leaving only small openings to allow a small amount of air to enter as the emulsion cools. When cool the drums are closed tightly.

The emulsion produced from formula A" contains approximately of solids. This concentration' is convenient but not critical. The concentration may be made higher, up to of solids and more, by stopping the addition of water when the desired concentration'has been reached.

The temperature during emulsiflcation should be maintained between 190 Fahrenheit and 210 Fahrenheit, since an inferior emulsion results if the emulsifying operation is allowed'to proceed at lower or higher temperatures.

The candelilla wax content may be increased to 12% or decreased to 7% if a corresponding ad- .lustment of the amount of soap is made. The paraffin content may likewise be varied between zero and 5%. The soap, although preferably formed in the presence of the waxes from red oil and sodium hydroxide solution may be added in the form of dry neutral sodium oleate soap flakes or grains, if water is added equivalent to that otherwise added with the sodium hydroxide.

The water for making the emulsion should be soft and should contain less than 100 parts of calcium carbonate per 1,000,000 parts of water, but if harder it can be softened preferably by a Zeolite process, by the lime and soda process, or by use of special chemicals such as alkali phosphates. Softening protects the soap in the emulsion and thus prevents breakdown later.

The rate of stirring should be rapid but not so great as to stir appreciable quantities of air into the emulsion since frothy liquids, not being homogeneous, do not dilute nor react satisfactorily.

A 100 gallon batch of shellac solution for combination with the wax emulsion may be produced In preparing the shellac solution about 687 lbs. of water and 22.50 lbs. of 26 B. ammonia water are put in a mixing tank. The water should have a temperature of approximately 120 Fahrenheit. The amount of ammonia water put in the tank is approximately 5 lbs. more than the theoretical requirement, since about 5 lbs of ammonia gas escapes during the process. The liquid is stirred and granulated shellac is gradually added while stirring until all soluble matter is dissolved. This requires approximately onehour. The solution is then strained through a 100 mesh sieve into a drum or container which is then closed tightly.

Relatively fresh shellac gives the best results. Shellac which has been stored for a few months is less suited since it appears to undergo a gradual change in composition which increases the difficulties of dissolving it and results in a solution which is less stable than a solution prepared from freshly refined shellac.

The solution keeps well in tight steel drums preferably stored in a cool place.

The amount ofv ammonia used should be suillcilent substantially to exceed the acidity of the s e lac.

The final concentrated coating composition is the cool wax emulsion "A" while stirring. The

stirring is continued slowly for ten to fifteen minutes in order to obtain a homogeneous emulsion in which each of the highly dispersed minute wax particles is surrounded by an envelope of shellac solution. Rolling of the steel drums may be substituted for stirring.

A representative formula for preparing gallons of concentrated coating fluid is as follows:

The resulting coating fluid contains 80% wax emulsion and 20% shellac solution. Its composition in terms of per cent by weight of constituents is as follows:

Candelilla wax araifin The concentrated solution and emulsion "D" contains approximately 15% of solids of which 2.85% is soap. These figures, however, may be varied to some extent. The solids may vary from 10% to and the soap content may vary between 2.5% and 4.5%.

The concentrated blend D may be drawn off into steel drums for storage and shipment. It is very stable and is not affected by considerable changes in temperature nor by storage for apv preciable periods of time. For the coating of fruit or vegetables it may be diluted by adding two to five parts of water to one part of concentrated blend D," best results being usually 'obtained with a ratio of one part of concentrated blend D and three parts of water.

The diluted coating emulsion has excellent wetting qualities and may be applied to fruit or vegetables merely by dipping or spraying. It produces a crystal clear film on the fruit of high lustre, high shrinkagecontrol and complete freedom from stickiness. The film requires no brushin; or rubbing and is for this reason admirably suited for the coating of soft skinned fruits and vegetables such as tangerine or tomatoes, which cannot be brushed or rubbed.

The fresh color and contogir oi the ripe fruit is retained for periods twic or three times as long as the time during which uncoated fruit retains its freshness. It is thus possible to preserve the freshness of fruits and vegetables over a period of at least two weeks as against barely 55 one week for uncoated fruit.

The coating is smooth, glossy and non-tacky due to the fact that eachwax particle which is normally sticky is coated by a thin film of shellac.

I am aware of the fact that shellac has previously been used as an ingredient in coating compositions for fruit, mainly for the purpose of enhancing lustre. In my particular novel coating composition/itprimarily insures the formation f I a non-tacky and glossy surface and inmdditi n increases the shrinkage-retarding properties of the composition.

While I have described preferred modifications of my invention and cited specific examples and formulae for the purpose of illustration, it is understood that these are merely examples and may be varied. I therefore do not wish to limit myself to these details. It will be understood that other and specifically different but equivalent substances may be employed witmiut departing from the spirit of this invention to produce emulsions acting in an analogous manner. All such modifications are considered to be comprehended .within the spirit and teaching of thi invention.

What is claimed is 1. The process of preparing an emulsion for application to fruit and vegetables to retard .decay and minimize shrinkage which consists in heating candelilla wax and oleic acid to a temperature between and 212 Fahrenheit; adding, while maintaining the temperature between 190 Fahrenheit and the boiling point, an aqueous solution of sodium hydroxide in an amount sufficient to saponify the fats and fatty acids; adding water under stirring of the mixture while maintaining a temperature between 190 and the boiling point until a dilution containing between 10% and 30% solids is reached; and adding an aqueous solution of shellac in ammonia.

2. The process as set forth in claim 1 in which there is added paraflin to the candelilla wax in an amount up to 25% by weight of said wax.

3. The process of preparing an emulsion for application to fruit and vegetables to retard decay and minimize shrinkage which consists in heating-candelilla wax, parafiln and oleic acid to a temperature between 190 and 212 Fahrenheit;

adding while maintaining a temperature of between 190 and the boiling point an aqueous solution of about "4N sodium hydroxide, the quantity being suflicient to produce a neutral mixture without residual free alkali; adding water under stirring of the mixture and maintaining a temperature .between 190 and 210 until a dilution is obtained containing between 10% and 30% solids, and admixing an aqueous solution of shellac in ammonia.

4. A coating ,emulsion particularly for fresh by the sodium hydroxide and oleic acid to the total of solids in/the emulsion being between 2.5 15 and 4.5 15.

6. A coating emulsion particularly for fresh fruit and vegetables to retard decay and minimize shrinkage containing candelilla wax, paraffin, shellac, neutral soap, and water.

'L A coating emulsion particularly for' fresh frui and vegetables to retard decay and minimize shri ge containing candellila wax, paraffln,

shellac, neutral soap, and water, the relative proportions of the soap to the total of solids in the emulsion being between 2.5/15 and 4.5/15.

8. A coating composition particularly for fresh fruit and vegetables to retard decay and minimize shrinkage containing, in, relative proportions, by

weight, candelilla wax 10 parts, parafiin to 2.5 5

parts, neutral soap to 4 parts, shellac to 4 parts ,1

and water.

9. A coating composition particularly for f esh fruit and vegetables to retard decay and mini e shrinkage, containing in relative proportions candelilla wax 'I to 10 parts, paraffin to 2.5 parts,

neutral soap as to 4.5 parts, shellac m4 parts.

10. In the process of preparing an emulsion particularly for application to fruits and vege- 7 tables to retard decay and minimize sfilnkaze, the emulsion containing candelllla wax, paraflln, and soap, the step of adding to the emulsion an aqueous solution of shellac and ammonia.

11. A coating emulsion particularly for fresh fruit and vegetables to retard decay and minimize shrinkage containing. in relative proportions, by weight, candelilla, wax to 10 parts, paramn to 2.5 parts, soap 2.5 to 4.5 parts, shellac 2 to 4 parts, ammonia and water.

JAMES OTIS HANDY.

REFERENCES CITED The following references are of'record 1n the file of this patent:

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